1. Field of the Invention
This invention relates to apparatus for and methods of repairing or relining metallurgical vessels, and more particularly to an improved work support platform including a safety shield adapted to be projected upwardly through the opening in the bottom of a metallurgical furnace such as a Q-BOF when the bottom plug is removed.
2. Description of the Prior Art
It is well known to employ a vertically adjustable work platform to support workers and materials at the desired elevation to reline or repair the refractory lining of a metallurgical furnace or converter. Converter vessels conventionally are constructed with a relatively large opening in the bottom wall which is closed during operation by a removable refractory lined plug. During relining or lining repair, this bottom plug is removed and the work platform apparatus is positioned directly beneath the opening in the bottom wall so that the platform can be projected upwardly into the converter.
The open top and the opening in the bottom wall are substantially smaller than the main body of a converter vessel. Accordingly, the work platform has conventionally employed some means for expanding the structure outwardly from the vertical elevator support. Personnel working on the platform thus may be working at a location beneath the inwardly tapered top or "hat" section of the converter so that, during repair, debris falling from the lining above can present a serious work hazzard. The prior art vertically adjustable work platforms have not included any means for shielding workers from such falling debris.
It is frequently necessary to repair only the bottom wall portion of the lining of a converter vessel, particularly the refractory rings adjacent the bottom plug of a Q-BOF. In making such repairs to the bottom wall, it is desirable to avoid cooling the converter more than necessary. In the past, however, heat radiation has prevented work even in the area adjacent the bottom opening until the converter has reached a relatively low temperature which could be tolerated by the unshielded workers.
U.S. Pat. No. 3,230,685 recognizes the danger to workers in a converter as a result of falling debris such as slag or fragments of the refractory lining, especially from the inwardly inclined wall portion adjacent the open top, and proposes to protect such workers by an inflatable cone-shaped ring which theoretically can be held in firm contact with the overhanging portion of the converter wall by a cable suspension system extending through the open top. The effectiveness of this inflatable, flexible hollow annular body for its stated purpose would appear to be at least questionable, however, in the absence of substantial rigid reinforcement to retain the flexible member in the desired configuration. Further, since the main wall of the converter is not contacted by the flexible member, this safety device would be largely ineffective in shielding workers repairing the bottom wall from radiated heat and falling debris from the main body of the converter.
It is the primary object of the present invention to provide an improved method of and apparatus for use in repairing the lining of a metallurgical furnace which avoids the foregoing and other defects of the prior art.
It is another object of the invention to provide a method of and apparatus for use in repairing the lining of a converter vessel in which workers are shielded from falling debris and heat radiated from the interior of the vessel above the level of the workers.
Another object of the invention is to provide an improved method of and apparatus for repairing the bottom wall of a converter vessel in which a radially expandable structural shield is initially telescoped into the interior of the vessel through the hole in the bottom wall and then radially expanded to provide an umbrella-like shield for workers supported on a work platform below the shield.
Another object of the invention is to provide such an apparatus for use in repairing the bottom wall of the converter vessel of a Q-BOF in which an umbrella-like protective shield may be lowered into contact with the bottom wall of the converter vessel outboard of the area being repaired and which permits ventilation through the bottom hole whereby repairs may be made to the bottom wall while the converter is maintained at a higher temperature than was previously practical.